Posterior corrections for classical MD and MC simulations

Prof. Petr Slavíček
(Department of Physical Chemistry University of Chemistry and Technology, Prague, Czech Republic)
‘Nuclear Quantum Effects in Spectroscopy’

Denis Tikhonov
(Department of Physical Chemistry, Lomonosov Moscow State University, Russian Federation)

In the conventional picture of the atom it is implicitly assumed that the atomic nuclei are point-like classical particles, whereas the only quantum objects are the orbiting electrons. Sometimes, such an approximation may not be valid anymore and the quantum nature of nuclei may be reflected. Nuclear quantum effects (NQEs), e.g. zero-point vibration, tunnelling, resonance, scattering, interference, etc., have a significant influence on the structure and dynamics of condensed matter systems, which impacts their observed properties with widely varying magnitudes. The microscopic origin and the corresponding temperature dependence of NQEs have been elusive and still remain subject of ongoing discussion from both experimental (neutron and photon spectroscopy) and theoretical (static and dynamic) perspectives. From the theoretical point of view, molecular dynamics (MD) is a powerful numerical method to investigate properties of condensed matter systems, being, however only valid in the classical limit and so for high temperatures. It is, however, necessary to include NQE to study the low temperature regime, the dynamics of light atoms (such as hydrogen) or the isotope effects. The method commonly used to simulate quantum dynamics is path integral molecular dynamics (PIMD), which is, however, particularly time consuming and therefore the range of its applicability is reduced. A new semi-classical approaches to account for NQEs have been recently proposed. This mini seminar is, hence, devoted to highlight the significance of NQE and discuss recent developments in the state-of-the-art experiments and theory.